UV-VIS absorption spectra are broad band spectra. Explain.
The visible region of the spectrum comprises photon energies of 36 to 72 kcal/mole, and the near ultraviolet region, out to 200 nm, extends this energy range to 143 kcal/mole. Ultraviolet radiation having wavelengths less than 200 nm is difficult to handle, and is seldom used as a routine tool for structural analysis.
The energies noted above are sufficient to promote or excite a molecular electron to a higher energy orbital. Consequently, absorption spectroscopy carried out in this region is sometimes called "electronic spectroscopy". A diagram showing the various kinds of electronic excitation that may occur in organic molecules is shown on the left. Of the six transitions outlined, only the two lowest energy ones (left-most, colored blue) are achieved by the energies available in the 200 to 800 nm spectrum. As a rule, energetically favored electron promotion will be from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO), and the resulting species is
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Write the values of four quantum numbers for 3d electrons.
Complete following equations:
- 30 P + ...→ 30Sii
- 10 B + n → .... + α
- 20 Ne + 136Ba → 150Dy + ....
- ..... + 2H→22Na + α
- 241Am + ...→ 243Bk + 2n
Predict the hybridization state of each carbon atom in allene which has the following structure:
CH2 = C = CH2
From the infrared spectrum given below, identify the possible functional groups corresponding to the peaks indicated in the arrows.
By writing molecular orbital configuration for each of following molecules calculate the bond order and also determine whether it is paramagnetic or diamagnetic.
(i) NO (ii) CO (iii) O2+
Draw all of the stereoisomers of 2,3-butandiol, label meso compounds and pairs of enantiomer.
The dipole moment of HBr is 2.60 ´ 10-30 C m and interatomic distance 141 pm. What is the percentage ionic character of HBr?